This application claims the benefit of the Korean Application No. P2002-32901 filed on Jun. 12, 2002, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a multi-unit air conditioner, and more particularly, to a multi-unit air conditioner having an improved outdoor piping system and an improved refrigerant mixing ratio controlling system, and a method for controlling the same.
2. Background of the Related Art
In general, the air conditioner is an appliance for cooling or heating spaces, such as living spaces, restaurants, and offices. At present, for effective cooling or heating of a space partitioned into many rooms, it is a trend that there has been ceaseless development of multi-unit air conditioner. The multi-unit air conditioner is in general provided with one outdoor unit and a plurality of indoor units each connected to the outdoor unit and installed in a room, for cooling or heating the room while operating in one of cooling or heating mode.
However, the multi-unit air conditioner is operative only in one mode of cooling or heating uniformly even if some of the many rooms within the partitioned space require heating, and rest of the rooms require cooling, the multi-unit air conditioner has a limit in that the requirement can not be met, properly.
For an example, even in a building, there are rooms having a temperature difference depending on locations of the rooms or time of the day, such that while a north side room of the building requires heating, a south side room of the building requires cooling due to the sun light, which can not be dealt with a related art multi-unit air conditioner that is operative in a single mode.
Moreover, even though a building equipped with a computer room requires cooling not only in summer, but also in winter for resolving the problem of heat load of the computer related equipment, the related art multi-unit air conditioner can not deal with such a requirement, properly.
In conclusion, the requirement demands development of multi-unit air conditioner of concurrent cooling/heating type, for air conditioning rooms individually, i.e., the indoor unit installed in a room requiring heating is operable in a heating mode, and, at the same time, the indoor unit installed in a room requiring cooling is operable in a cooling mode.
Accordingly, the present invention is directed to a multi-unit air conditioner and a method for controlling the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a multi-unit air conditioner which cools and heats rooms individually suitable to individual room requirements, and has very simple outdoor unit system.
Another object of the present invention is to provided a method for controlling operation of a multi-unit air conditioner, in which a gas-liquid mixing ratio of refrigerant introduced into a gas-liquid separator is optimized in an operation of cooling all rooms and cooling a major number of rooms and heating a minor number of rooms, for improving an air conditioning efficiency.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the multi-unit air conditioner includes an outdoor unit including a flow path control valve for controlling a flow path of refrigerant from a compressor, outdoor heat exchanger having one side in communication with the flow path control valve, a first bypass pipeline having one end connected to the first pipeline which makes the flow path control valve and the outdoor heat exchanger to be in communication, and the other end connected to the second pipeline connected to the other end of the outdoor heat exchanger, and a flow rate control valve provided on the first bypass pipeline for controlling a flow rate of the refrigerant passing through the first bypass pipeline, an indoor unit having an indoor heat exchanger and indoor electronic expansion valve installed in each of rooms, a distributor for selective distribution of the refrigerant received through one of two pipelines connected to the outdoor unit to the indoor units, and returning to the outdoor unit through the other one pipeline, and controlling means for measuring a gas/liquid mixing ratio of the refrigerant introduced into the distributor, the refrigerant having joined after respectively passing through the first bypass pipeline and the outdoor heat exchanger, for controlling an opening of the flow rate control valve, to control the mixing ratio.
The operation mode includes a first operation mode for cooling all rooms, a second operation mode for heating all rooms, a third operation mode for cooling a major number of rooms and heating a minor number of rooms and a fourth operation mode for heating a major number of rooms and cooling a minor number of rooms.
The distributor is made to be in communication with the outdoor unit with a fourth pipeline having one end connected to the flow path control valve and a second pipeline having one end connected to the outdoor heat exchanger.
The flow control valve includes a first port in communication with an inlet of the compressor, a second port connected to the first pipeline, a third port having one end connected to the other end of the third pipeline connected to an outlet of the compressor, and a fourth port connected to one end of the fourth pipeline.
The flow path control valve makes the outlet of the compressor and the first pipeline in communication, and the third and fourth pipelines in communication in the first and third operation modes.
The flow path control valve makes the outlet of the compressor and the fourth pipeline in communication, and the first and third pipelines in communication in the second and fourth operation modes.
The indoor unit further includes an accumulator mounted on the third pipeline.
The controlling means includes a temperature sensor provided on the second pipeline for measuring a temperature of gas/liquid mixed refrigerant joined after respectively passing through the outdoor heat exchanger and the first bypass pipeline, and a microcomputer for comparing the refrigerant temperature measured by the temperature sensor and a preset refrigerant temperature, to detect the gas/liquid refrigerant mixing ratio, and controlling an opening of the flow rate control valve for making a detected mixing ratio to meet the preset mixing ratio required for a required operation mode.
The flow rate control valve is fully closed in the first, second, or fourth operation mode, and has the opening thereof controlled by the microcomputer in the third operation mode.
The outdoor unit further includes a first electronic expansion valve mounted on the second pipeline between the other end of the outdoor heat exchanger and the first bypass pipeline, and a first check valve mounted in parallel with the first electronic expansion valve for passing refrigerant flowing only from the outdoor heat exchanger toward the distributor.
The first electronic expansion valve is controlled such that the first electronic expansion valve is fully closed in the first or third operation mode, and expands the refrigerant flowing from a distributor side to an outdoor heat exchanger side in the second or fourth mode.
The distributor makes the gas refrigerant introduced thereto from the outdoor unit to flow toward indoor unit heat exchangers which are to heat the rooms, the liquid refrigerant introduced thereto from the outdoor unit toward electronic expansion valves of the indoor units which are to cool the rooms, and the refrigerant passed through the indoor units to flow to the outdoor unit again, wherein, in a case heating or cooling of the rooms are carried out individually, the refrigerant liquefied as the refrigerant passes through the indoor unit which is to heat the room is made to flow toward the electronic expansion valve of the indoor unit which is to cool the room before making the refrigerant to flow to the outdoor unit.
The distributor includes a gas-liquid separator connected to the second pipeline for separating gas/liquid mixed refrigerant received from the second pipeline into gas refrigerant and liquid refrigerant, a distribution piping system for guiding the refrigerant from the outdoor unit to the indoor units, and from the indoor units to the outdoor unit, and a valve unit on the distribution piping system for controlling flow of the refrigerant in the distribution piping system to be consistent with respective modes.
The distribution piping system includes a gas refrigerant pipeline connected to a gas port of the gas-liquid separator, a liquid refrigerant pipeline connected to a liquid port of the gas-liquid separator, liquid refrigerant branch pipelines branched from the liquid refrigerant pipeline and connected to the indoor expansion valves in the indoor units respectively, gas refrigerant branch pipelines branched from the gas refrigerant pipeline and connected to the indoor heat exchangers, respectively, and connection pipelines respectively branched from the gas refrigerant branch pipelines and connected to the fourth pipeline.
The distributor further includes a second bypass pipeline having one end connected to the liquid refrigerant pipeline adjacent to the liquid port, and the other end connected to the gas refrigerant pipeline adjacent to the gas port, a second check valve on the liquid refrigerant pipeline between the one end of the bypass pipeline and the liquid port, for making the refrigerant to flow from a liquid port side toward the liquid refrigerant branch pipeline side, and a second electronic expansion valve on the second bypass pipeline.
The second electronic expansion valve is controlled such that the second electronic expansion valve is closed fully in the first or third operation mode, and causes the refrigerant to expand in the second or fourth operation mode.
The valve unit includes a plurality of on/off valves on the gas refrigerant branch pipelines, the liquid refrigerant branch pipelines, and the connection pipelines.
In another aspect of the present invention, there is provided a method for controlling a multi-unit air conditioner comprising the steps of (a) condensing a portion of gas refrigerant from a compressor at an outdoor heat exchanger, making the other portion to flow through a bypass pipeline in a gas state, and joining the condensed refrigerant and the gas refrigerant, (b) measuring a temperature of the joined gas/liquid mixed refrigerant, (c) detecting the gas/liquid mixing ratio from the measured refrigerant temperature, and (d) controlling a flow rate of the gas refrigerant such that a detected mixing ratio meets a preset mixing ratio required for a required operation mode.
The step (c) includes the step of comparing a preset data on refrigerant mixing ratios versus refrigerant temperatures and the measured temperature, to detect the mixing ratio of the refrigerant. The step (d) includes the step of controlling an opening of the flow rate control valve on the: bypass pipeline for controlling a flow rate of the gas refrigerant flowing through the bypass pipeline.
It is to be understood that both the foregoing description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention claimed.